Microparticles (MPs) result from plasma cell membrane remodeling and shedding after cell stimulation or apoptosis. MPs are know recognized as a pool of bioactive messengers with emerging role in pathophysiology of immune and cardiovascular diseases. MPs have been characterized during septic shock and may contribute to dissemination of pro-inflammatory and procoagulant mediators. This is a prospective observational study of circulating MPs and blood coagulation in 100 septic shock patients admitted in 3 tertiary hospitals medical ICU at baseline (D1), D2, D3, D4 and D7.